The present invention relates to a thermo-magnetically-treated anisotropic permanent magnet alloy comprising iron, chromium, cobalt and silicon as main components, which has a good workability and is easy to heat treat, and to a process for the production thereof.
At present, permanent magnets are practically used mainly for motors, various meters and electric devices, but magnetic properties required may vary broadly depending upon the nature of final uses. Therefore, there are too many kinds of permanent magnet alloys having such magnetic properties. Practically, however, typical alloys are chosen depending upon the degree of coercive force required. For example, in order to obtain coersive force required, an appropriate alloy is selected from the group of Fe-Mn-Ti alloys, Fe-Co-V alloys, Fe-Ni-Cu alloys, Alnico alloys and rare earth-cobalt sintered alloys.
Fe-Mn-Ti alloys have good workability but have relatively low coercive force, such as 50 to 160 Oersted. It is well known that Alnico alloy can not only cover broad ranges of magnetic properties when compositions thereof are changes, but also is the most commercially available, but they are too hard and are too brittle to be machined and, therefore, poor in workability.
Fe-Co-V alloys, i.e., so-called "Vicalloy" are famous as magnets having a good workability, but they have only one and great defect of being expensive because of containing more than 50% cobalt and more than 10% vanadium.
Fe-Ni-Cu alloys, i.e., so-called "Cunife" have an excellent workability, and they can readily have a high coersive force, but can have only a relatively lower residual magnetic flux density. Therefore their uses are restricted.